P2496 - AtCoder166 C - Peaks

Memory Limit：128 MB Time Limit：1.000 S

Judge Style：Text Compare Creator：

Submit：5 Solved：5

There are

N

observatories in AtCoder Hill, called Obs.

1

, Obs.

2

. . .

..., Obs.

N

. The elevation of Obs.

i

_{i}

. There are also

M

roads, each connecting two different observatories. Road

j

connects Obs.

_{j}

and Obs.

_{j}

.
Obs.

i

is said to be good when its elevation is higher than those of all observatories that can be reached from Obs.

i

using just one road. Note that Obs.

i

is also good when no observatory can be reached from Obs.

i

using just one road.
How many good observatories are there?

Input is given from Standard Input in the following format:

N M
H1 H2 ......HN 
A1 B1
A2 B2
::
AM BM

Print the number of good observatories.

2496: AtCoder166 C - Peaks